Mirror wheel for television systems



March 22, 1932. A, KAROLUS 1,850,629

MIRROR WHEEL FOR TELEVISION SYSTEMS Filed April 19, 1950 INVENTOR A TORN'EY Patented lVla.r.2?.., 19321 UNHTED STATES PATENT" OFFICE AUGUST KAROLUS, OF IIEIPZIG, GERMANY, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATION OF.DELAWARE V MIRROR WHEEL FOR TELEVISION SYSTEMS I Application-filed April 19, 1930, Serial No. 445,540, and in Germany May 1,1929.

The present invention relates to television systems, and, in particular, to thescanning devices used therein. According to the present development in the television art, the so- 5 called mirror ,or reflector wheel forms an essential part of many of the modern televis on installations. Such a mirror wheel conslsts of'a polygonal prism revoluble about its axis and whose shell or circumference carries mirrors or reflectors of small size. As the mirror polygon thus constructed is rotated, all of the mirrors are consecutively caused to pass through a relatively small zone where V the pencil of light rays falling upon a given mirror is reflected on to the picture surface which it passes or scans along a line in accordance with the motion of the mirror. I If all ofthe mirrors are positioned exactly in the plane of the wheel shell, then to scan the entire projection surface bythe ray pencil, a second mirror wheel is required having its shaft or spindle positioned at right angles to the former in order to collect the scanning pencil moving along or in thedirection of one dimension of the picture projection surface and to impart to it also motion in the direction of the other dimension. However,

a construction of mirror wheel which is particularly advantageous is one in which the constituent mirrors do not fall exactly in the plane of the prism shell, or,cin other words, in which all of the mirrors are not positioned parallel to the axis of rotation, but 'present different angles of inclination of small size in'relation to the axis of rotation. As aresult, the lines along which the light ray pencils'r'efiected from different mirrors of a mirror wheel travel over or scan the projection surface of the pictureconsecutively will not 40 coincide, so that in this form of construction only one mirror wheel will be required for insuring complete scanning and exploration of the projection surface in a line for line manner. V

Since the corresponding points of the picture projection surface at thertransmitter and the receiver end must be scanned practically simultaneously, care must be taken to provide driving arrangements so arranged that the 5 mirror drum systems of both parts of the televisor equipment will revolve in perfect synchronism. For the drive of the. mirror wheel recourse is usually had to synchronous motors which are maintained in perfect synchronism by the aid of tuning forks or other suitable constant-frequency means.

A drive of this kind usually comprises a D. C. shunt-wound motor which supplies the major part of the drive energy, and a synchronous motor which is subject to tuning 6Q fork or other constant frequency. With these systems, the synchronous motor control furnishes only the energy required to insure absolute synchronous rotation.

From the above, it is, of course, apparent 55' that my invention has as one of its primary objects that of providingsimpler and more efficient means for driving the television scanning element. Other objects will suggest themselves and become apparent from a read- 7 ing of the following specification and claims in connection with the accompanying draw ings, indicating several of the many forms which the invention may assume.

By the drawings, Fig. 1 represents the usual-D; C. motor drive and synchronous motor control;

, Figs. 2 and 2a represent in a schematic manner the construction according to my present invention, wherein the scanning elementis formed as apart of the rotor of the drive mechanism;

Fig. 3 represents one practical form of the invention schematically shown by Fig.2;

Fig. 4 represents a modification of the form of invention shown by Fig. 3;

Fig. 4a is a sectional view of the arrangement of Fig. 4, taken on the line 4a4a thereof;

Fig. 5 is a further modification of the arrangement of Fig. 3; and,

Fig. 5a represents a section of Fig. ,5, taken on the line 5a5a thereof.

Now, by referring tothe drawings and first to Fig. 1, illustrating a drive of this kind as known in the prior art, SR denotes the mirror wheel which is in'mechanical coupling relationship through a clutches KK with a D. C. motor GM and a synchronous motor SM. Under certain circumstances, the D. C. motor a may be dispensed with so that the entire drive is taken over by the synchronous motor, it having to be noted that the driving energy required by such a mirror-wheel mechanism is ordinarily but small, and, in fact, apart from the, electro-magnetic losses of the driving motor, it is, in the main, due to windage and bearing friction of the revolving parts. It is important to reduce the required driving ener to as low ameasure:asfeasible.

According to the present invention, this is made feasible by the aid of an improved form of construction in which the mirror wheel and its drive mechanism is united to form a. single apparatus unit in such a way'that the stator member of the electric drive is disposed inside the mirror wheel, while the innor wall of the mirror drum surounding said stator member is so designed as to act as a rotor.

By the adoptionof thisform of construction, the size of the revolving masses and surfaces resulting in windage as well as the number of supports .and bearings is minimized; and, also, the spacerequirement of the entire outfit is reduced.

.Inthe majority of cases when practicing this scheme, it will be sufficient to provide merely a synchronous motor for the drive. Themechanical end ofthe object of this invention and an embodiment thereof is shown in roughly schematic form in the accompanyin drawings by Figs. 2 and 2a.

In the arrangment illustrated in Fig. 2, the wheel 1' bearing the mirrors a is fixedly united with the shaft b whichis revolubly supported in the bearings? and Z most preferably bearin s of the hall or roller type. The inner wall is designedto act as a rotor member formin part of an electromagnetic drive, and insi ethis rotor is mounted the stator 8 being most suitably supported by ball or roller hearings on a shaft 6, in such a manner that it will not partake of the rotation of the said shaft 6. In order to insure erfect co-phasal relation between the two rive mechanisms provided atthe sending and atthe receiving ends, it is necessary thatthe stator member 8 should be disposed so as to be capable of adjustment. This may be efiected in any desired manner, for example, the gear-wheel rim 0 mounted at some suitable point of the stator is. set through a pinion d in meshing relation therei with and a setting wheel a, whereupon it should be adapted to be locked in the desired position.

The arrangement shown in Fig. 2a differs from the foregoing essentially only in that here the shaft 6 is fixedly connected with with the stator s and not with the mirrorwheel 1' and that it is passed through the hub or boss 1 preferably supported by ball or roller bearings. In this form of construction, the bearings 1 and Z need not be designed as ball bearings. The device e serving for turning and locking the stator 8 may here be attached to one of the butt ends of the shaft 7).

The construction of the electromagnetic part of the motor drive may be of widely different kind. For instance, the stator and the rotor in a way known in the prior art may be provided with teeth gearings comprisin the same number ofteeth and being placed opposite each other, each tooth, or every other tooth, of one motor member being furnished with a D. C. winding and the other one with an A. (lwinding. However, it is preferable to use a type of construction in which, at least inone motor member, the complicated and tedious wrapping of a winding around some of the teeth is avoided, or wherein the motor member has no winding at all. Among the types suited for this purpose may be mentioned here the claw type, the O-type and the phonic wheel.

Now -makin reference to Fig. 3, which illustrates a si e elevation, partly in vertical section, of a synchronous motor of the clawpole type built into the mirror wheel 1' according to this invention, the rotor is here furnished with teeth in which the A. C. winding w, here supplied through slip rings h, is accommodated. The stator consists of two rings laid together, m1 and m2. The claw poles n1 of the ring m1 are of one polarity, and the claw poles n2 of the ring m2 are of the other polarity. The claw poles of one polarity engage the spaces or notches of'the convenient extension p of the bearing Z or else, as shown in Fig. 4 and Fig. 5, directly in the said bearing.

In the case of the embodiment shown by way of example in Figs. 4 and 4a, the built-in synchronous motor is of what is known as the O-type. The rotor teeth 2, are unwound. The stator 8 has a D. C. exciting coil g disposedin a way similar to the preceding embodiment and fed by way of the slip rings f, and an A. C. winding 10 fed by wayof-the slip rings 72. and disposed on the stator teeth 2,.

In the embodiment shown by way of example in Fig. 5 and Fig. 5a, the drive consists of an application of the principle underlying the so-called phonic wheel. As shown in the drawings the rotor has been furnished with a continuous dentat-ion, though the constituent or strips of soft iron disposed along the shell line of the inner cylindrical wall of the drum wheel and separated from one another. The stator here consists of any desired number of electromagnets terminating in points it ning element mounted on the outer periphery of said rotor.

4. An optical apparatus comprising a motor having an internal stator and an external rotor, an optical analyzing element carried and secured upon a boss or hub't, the latter, 111 11 the outer periphery of said rotor, and

if desired, being adjustable by the agency of tooth wheels 0 and (Z; The number of said electromagnets is governed according to the amount of driving force that is required, in-

deed, under certain circumstances, the provision of a single electromagnetic pole u may suifice. v

In the present example, an electromagnet having two prongs s1, s2, terminating in points H is shown; 9 denotes the D. C. winding and w again the A. C. winding. It is well-known, however, that motor action is producible also by a single winding if a rhythmically pulsating D C. is sent therethrough.

To reduce windage or air resistance in all of the embodiments hereinbefore cited, the gaps between teeth or notches may be filled up by suitable non-magnetic material so that all of the surfaces essentially responsible fo windage are thus rendered smooth.

In all of the embodiments shown in Figs. 3 et seq. the mirror wheel 1' is shown as keyed upon the shaft 7) in accordance with the me chanical scheme shown by Fig. 2. though it will be understood that in all of these cases recourse could be had also to an arrangement asshown in Fig. 2a.

If a D. C. motor is desired in addition to the synchronous motor, then the former may be mounted inside the mirror-wheel similar- 1;; and adjacent to the latter, though, as a general rule, this will be found unnecessary inasmuch as the synchronous motor, because of the small amount of energy that is required, will suflice for the drive. In order that the mechanism may be brought to synchronous speed, an electrical or mechanical device transiently coupled for starting or else a manual drive may be resorted to.

If desired, synchronous start may be secured in well-known manner by a suitably arranged, auxiliary winding.

Having now described my invention, what I claim and desire to secure by Letters Patcut is the following:

1. An optical apparatus comprising a motor having an internal stator and an external rotor, and an optical analyzing element in tegral with the outer periphery of said rotor.

2. An optical apparatus comprising a synchronous motor having an internal stator and an external rotor, and an optical analyzing element carried upon the outer periphery of said rotor.

3. An optical apparatus comprising a synchronous motor having an internal stator and an external rotor, and an opticalscanthereof.

AUGUST KAROLUS. 

